Understanding Radon Gas Risk in Metro East Illinois Homes

When you live in the Metro East area, the rolling hills and river bluffs make for beautiful scenery. But those same geological features can also create a hidden hazard beneath your home. I have spent years working with homeowners in Belleville, Edwardsville, O'Fallon IL, and Collinsville, and the most common surprise they face is the presence of radon gas. It is colorless, odorless, and tasteless, which makes it easy to dismiss. Yet the radon gas risk in this part of Illinois is very real, and understanding it can make a major difference in your family's health.

What Makes Radon Gas a Problem in the Metro East?

Radon comes from the natural decay of uranium in soil and rock. The Illinois Geological Survey has mapped areas where the underlying geology is more likely to produce radon, and much of the Metro East falls into zones with moderate to high potential. When radon gas seeps up through the ground, it can enter your home through cracks in the foundation, gaps around pipes, or even through the slab itself. Once inside, it can accumulate to levels that pose a health concern.

The EPA has set a recommended action level of 4 picocuries per liter of air. Above that threshold, they advise taking steps to reduce the radon gas risk. In my experience testing homes across Belleville, Edwardsville, O'Fallon IL, and Collinsville, I have seen levels well above that number. One home near the bluffs in Collinsville tested at 12 pCi/L. Another in a newer subdivision in Edwardsville came in at 7 pCi/L. These are not rare outliers. They are common enough that every homeowner should take the matter seriously.

Testing Is the Only Way to Know

You cannot guess whether your home has a radon problem. The only reliable method is to perform a test. There are two main approaches: short-term tests and long-term tests. A short-term test typically lasts between two and seven days. It gives you a quick snapshot, which is useful if you are in the middle of a real estate transaction or just want a preliminary reading. A long-term test runs for more than 90 days and gives a more accurate picture of your year-round average exposure. The EPA recommends starting with a short-term test, and if the result is 4 pCi/L or higher, following up with a long-term test or a second short-term test to confirm.

You can buy a radon test kit at most hardware stores or online. These kits are inexpensive and simple to use. You place the detector in the lowest livable level of your home, such as a basement or a first-floor room if you have a crawlspace instead. You leave it undisturbed for the required time, then mail it to a lab. Within a few weeks, you get a report. Some homeowners prefer a digital radon detector that gives continuous readings, which can be helpful if you want to track changes over time. Air Sense Environmental also offers professional testing, which includes placing multiple detectors and providing a detailed analysis. Either way, the cost is small compared to the peace of mind you gain.

When a Test Shows a Problem

If your test comes back above 4 pCi/L, do not panic. Radon levels can be reduced, often with a well-designed radon mitigation system. The most common approach for homes with a basement or a slab-on-grade foundation is sub-slab depressurization. This technique, sometimes called soil suction, involves drilling a small hole through the basement floor, creating a suction point underneath the slab, and using a fan to pull radon-laden soil gas away from the home and vent it safely above the roofline. The system is surprisingly quiet and unobtrusive once installed.

For homes with a crawlspace, the approach is different but equally effective. A passive radon system relies on natural air pressure differences and the stack effect to draw radon out from under the house. An active radon system adds a fan to create a more consistent vacuum. In either case, the goal is the same: to prevent radon gas from entering your living space in the first place. After installing a system, it is wise to perform a follow-up test to confirm the levels have dropped below the action level.

I have seen these systems bring a home from 15 pCi/L down to 1.5 pCi/L or lower. The difference is dramatic, and the ongoing cost of running a small fan is minimal, often less than the cost of a monthly coffee habit. For homeowners in the Metro East, where basements are common and the soil is often clay-heavy, a properly installed mitigation system can be a long-term solution that adds value to the property.

Who Should Test and How Often

The EPA recommends that every home be tested for radon, regardless of age, location, or construction type. I would add that if you have never tested, you are overdue. Even if you bought a house that passed a radon test at the time of sale, conditions can change. Soil settles, new cracks form, and remodeling can alter the pressure dynamics of your home. I recommend retesting every two years, or after any major renovation that affects the foundation or the HVAC system.

Renters should also be aware of the radon gas risk. If you lease a home or an apartment in a basement level, ask your landlord if the property has ever been tested. In many states, including Illinois, there is no legal requirement for landlords to test, but it is in their interest to ensure a safe living environment. If you are building a new home, ask your builder about including a passive radon system during construction. The cost is much lower when done upfront, and it can later be converted to an active system if needed.

Common Misconceptions About Radon

One myth I hear often is that radon is only a problem in older homes. That is false. New homes can have radon issues too, sometimes even higher levels because they are built tighter for energy efficiency. Tighter construction reduces air exchange with the outside, allowing indoor radon to accumulate more easily. Another myth is that radon only affects basements. While it is true that radon levels are usually highest in the lowest part of the house, it can migrate to upper floors through stairwells, ductwork, and elevator shafts. Testing only the basement gives you a good starting point, but if you spend a lot of time on the main floor, you might want to test there as well.

Some people think that because their neighbor tested low, their own home will also be low. Radon levels can vary significantly even between adjacent houses. The soil composition, the foundation depth, and the way the home is heated all play a role. That is why the only reliable approach is to test your own home. Air Sense Environmental has seen this firsthand: two identical houses on the same street, one with a reading of 2 pCi/L and the other at 8 pCi/L.

Taking Action Without Overreacting

Understanding the radon gas risk in your home does not mean you need to live in fear. It simply means you should be informed and proactive. Testing is easy and inexpensive. If the results call for mitigation, the solutions are well established and effective. The key is to avoid the trap of doing nothing because the problem feels invisible. I have met too many homeowners who put off testing for years, only to discover that they have been living with elevated radon for a long time. The good news is that it is never too late to act.

If you live in Belleville, Edwardsville, O'Fallon IL, Collinsville, or anywhere else in the Metro East region, I encourage you to start with a test. You can do it yourself with a radon test kit, or you can hire a professional. Either way, the first step is the same: measure what is there. Once you know, you can decide what to do next. And that knowledge alone is worth the effort.